While denture forming technics and processing methods are known, none to our knowledge have a complete system to fabricate a custom denture which eliminates the materials, time and skill that this technic does.
In 1939 the Dupont Company and the Rohm and Haas Company marketed a methylmethacrylate and called it lucite, the forrunner of acrylic resins today. The material was made in powder form and a liquid of the same composition added for mixing. The two items used in the right proportion and correct manipulation was injected into a mold which contained artificial teeth and cured into some of several curing technics of applying time and temperature of several hours to produce a hardened base which would have artificial teeth attached. In 1948 a slight change in the monomer system brought about a self-curing material. The acrylic resin is used all over the world today and with only slight changes and improvements since the original conception. The improvements are pour type, soft liners and cross linked acrylic resin.
The usual process of fabricating a prosthesis commences when a dentist takes impressions of the patient's edentulous maxillary and mandibular arches. These impressions are negative imprints of the arches and become the moulds into which the gypsum material for the positive dental cast is poured. These positive casts are duplicates of the patient's arches and become the primary model to which the prosthesis is to be constructed.
In order to construct a prosthesis these dental casts are normally mounted in a dental articulator in order that the maxillary and mandibular casts are maintained in the same anatomical relationship as in the mouth of the patient. Another reason why the dental casts are mounted in the articulator is to permit the arrangement of the individual denture (false) teeth into their proper position for occlusion. These individual denture teeth are set in wax. On the master cast or model, wax is placed to provide for proper thickness for the denture base and refined by carving to conform to the patient's mouth. This completely waxed denture and cast is then invested in one-half of a metal denture flask with plaster. After this is hardened a separator is applied. The second half of the flask is then filled with plaster. This mix is also allowed to harden. The completed flask is then submersed in boiling water and after sufficient time the two halves of the flask are separated. The remaining wax is removed and the mold is meticulously cleaned with soap and boiling water.
A coating is applied to the mold to shield the acrylic resin from the moisture in the plaster. A proper mix of acrylic resin is made and placed in the mold and by means of pressure is trial packed until sufficient acrylic resin is contained in the mold, this could take several trials.
These flasks under pressure are placed into a curing unit for up to 12 hours depending on manufacturer's specifications. After a cooling period the mold is removed from the metal flask, the hardened plaster is carefully cut to allow removal of the cured denture. The master cast is then removed from the denture. The excess hardened acrylic resin is then removed and polished.